Method of removing metals from hydrocarbon feedstock using esters of carboxylic acids

Abstract

Method of removing metals from hydrocarbon feedstock using esters of carboxylic acids, and additives for the same, are provided, wherein hydrocarbon stream such as crude oil containing metals and slats thereof, such as calcium and calcium naphthenate, is mixed with an effective metal-removing-amount of an aqueous extraction-solution of non-precipitating and non-fouling additive comprising a chemical compound selected from a group consisting of methyl or ethyl or propyl or isopropyl mono- and / or di-esters of any of three carboxylic acids, such as, maleic acid, maleic anhydride, or fumaric acid or an appropriate combination of said esters, or an appropriate combination of any of said esters with any of said three acids, enabling formation of a hydrocarbonous phase and an aqueous phase containing the metal ions; and separating aqueous phase.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation application of International Application No. PCT / IN2009 / 000062 filed Jan. 23, 2009, entitled “Method of Removing Metals from Hydrocarbon Feedstock Using Esters of Carboxylic Acids,” claiming priority of Indian Patent Application No. 166 / MUM / 2008 filed Jan. 24, 2008, which applications are incorporated by reference herein in their entirety.FIELD OF INVENTION[0002]The present invention is generally related to the field of hydrocarbon industry and particularly related to removal of metals from hydrocarbon feedstock and more particularly to removal of calcium from the same.BACKGROUND OF INVENTION[0003]Considering the rising prices of crude oil, the refiners are forced to process opportunity crude such as DOBA, to be competitive. However these opportunity crudes pose many problems such as fouling of heat exchangers, difficulties in effluent treatment, poisoning of catalyst by certain metallic salts and such o...

AI Technical Summary

Benefits of technology

[0023]An object of the present invention is to provide an economical method with increased efficiency due to lesser dosage of the chemical compounds used, and to provide novel invention-additives to be used for calcium removal.

[0024]Another object of the present invention is to provide an efficient method to prevent precipitation of calcium salt in hydrocarbon phase or water phase, in use of some esters of carboxylic acids, and to provide novel invention-additives for calcium removal, and which are non-fouling and non-corrosive.

Problems solved by technology

However these opportunity crudes pose many problems such as fouling of heat exchangers, difficulties in effluent treatment, poisoning of catalyst by certain metallic salts and such other problems.

Among the metals, calcium poses very serious problems which cannot be tackled using the current refinery processes.

The crude is usually contaminated from several sources, including, metals including calcium, zinc, silicon, nickel, sodium, potassium, and such other metals.

Crude oil that contains a high percent of particulate solids can complicate the desalting process.

However, much of the solids in a crude oil from a field exist in tight water-in-oil emulsions.

That is, oil-wetted solids in high concentration in the crude may help form tight oil and water emulsions that are difficult to resolve.

The rag layer inside the desalter vessel may grow to such an extent that some of it will be inadvertently discharged with the water phase.

This is a problem for the waste water treatment plant since the rag layer still contains a high percentage of unresolved emulsified oil.

In addition to complicating the desalter operation, phosphorus and other contaminants are of particular concern to further downstream processing.

Basic metals such as calcium, when present in crude oil can lead to fouling of heaters and heat exchangers and poison catalysts used in crude processing.

However, oil-soluble metal salts such as naphthenates and phenolates are not removed by conventional desalting.

Therefore, oil-soluble, basic metal-rich crudes are less valuable than crudes with low levels of such metals.

A few, but increasingly important, petroleum crude feedstocks, residua, and deasphalted oil derived from them, contain levels of calcium or iron which render them difficult, if not impossible, to process using conventional refining techniques.

These organometallic compounds are not separated from the feedstock by normal desalting processes, and in a conventional refining technique they can cause the very rapid deactivation of hydroprocessing catalysts.

This adds to the cost of the process due to time involved and equipments and chemicals used in the process and such other factors.

The higher dosage will lead to higher cost.

Other disadvantage of using additives having a tendency to precipitate is that it will be difficult to control the dosage at the desired level in the equipments in the field, such as crude desalter, and hence additive will have to be used always in excess.

However, the disadvantage of the use of these acids and derivatives as additives compound, as seen from the experiments conducted by the present inventor to remove calcium from calcium napthenate from hydrocarbon feedstock, is that these acids require higher dosages as additive compound since they are to be used in 2:1 molar ration with respect to calcium.

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